The present invention relates to micromagnetic circuits. More particularly, it relates to magnetic circuits in which a miniaturized magnetic conductor is disposed in the proximity of an electrical conductor for forming a magnetic path for a magnetic field related to the one produced by the electrical conductor.
Comprehension of the present invention will be enhanced by a description of the terms used herein. A magnetic field can be represented by lines called lines of induction. Lines of induction generally follow a path of least resistance (e.g., through higher permeability material) around the conductor producing the magnetic field. A line of induction closes on itself, not at a terminal as in an electric field. The region occupied by the lines of induction is called a magnetic circuit.
To create a path for the magnetic circuit, it has long been known to position a magnetic conductor in the magnetic field created by a coiled electrical wire. This technique is seen in traditional electromagnetic devices such as inductors and transformers.
For example, in the well-known toroidal ring seen in FIG. 1, an electrical conductor 2 is wrapped around a magnetic conductor 4 having a higher permeability than the air around it. When the electrical conductor is closely wound and an electrical current passed therethrough, practically all of the lines of induction are confined to the magnetic conductor ring 4, thereby creating the magnetic circuit indicated by the arrows inside the ring.
It is also known that the size of the magnetic conductor itself causes eddy current and hysteresis loses in the magnetic conductor. Techniques to reduce these losses have focused on improvements to the traditional magnetic devices such as partitioning the magnetic conductor and choosing magnetic conductor material having a higher permeability and higher electrical resistance.
The present invention completely revolutionizes these known techniques. Briefly, the magnetic conductor is now arrayed in strips about the electrical conductor to form paths for the magnetic field. The magnetic conductor forming the path may include amorphous material having very high permeability, low magnetic reluctance, and relatively high electrical resistance. Moreover, because the path for the magnetic circuit may be thousands of times more inviting for the lines of induction than the ambient air, only a microscopic strip of the magnetic conductor material may be needed. (A "microscopic strip" has a microscopic sized cross-sectional area and a length appropriate for the specific application.) For example, as seen in FIGS. 2 and 3, one or more strips 12 of high permeability magnetic conductor may be disposed in a proximate relation to an electrical conductor 14. The strips 12 may have any cross-sectional shape, such as a rectangle or a circle, and may range in cross-sectional size from several Angstroms thick (t) and several thousand Angstroms wide (w) to much larger dimensions in diameter. Each strip may be, for example, a deposited layer (i.e., a "painted" strip) or a small filament such as microwire.
The magnetic circuit of the present invention may take numerous forms and have countless applications. In its simplest embodiments, it may take two general forms; a closed circuit in which the strips generally form bands around the electrical conductor (see, for example, FIG. 2), and an open circuit in which the strips are arrayed linearly adjacent the electrical conductor (FIG. 3). The closed circuit form creates a closed path for a magnetic field and may be used to make electrical conductors more inductive in, for example, inductive wires, a variety of antennas, antenna ground planes, and inductive surfaces. In its open circuit form the present invention collects a portion of an existing magnetic field (i.e., by providing a high permeability path) and may be used in, for example, magnetic sensors and direction finding antennas. In either form, the circuit of the present invention is particularly useful for miniaturizing traditional inductive devices such as antennas and inductors. Further, the permeability of the microscopic strips is relatively insensitive to frequency variation and thus the present invention is particularly suited for antennas covering a wide range of frequencies. Smaller cross-sections may be appropriate when the present invention is to operate at relatively low power with frequencies up to several gigahertz. Larger cross-sections may be appropriate when the present invention is to operate with relatively high power at lower frequencies (e.g., a kilohertz).
Accordingly, it is an object of the present invention to provide a magnetic circuit that obviates the problems of the prior art and that provides a microinductive device for countless applications.
It is yet another object of the present invention to provide a magnetic circuit that creates microscopic paths for a magnetic field around an electrical conductor.
It is still another object of the present invention to provide a magnetic circuit that provides microscopic paths for electromagnetic waves.
It is a further object of the present invention to provide a miniaturized antenna that is responsive to electromagnetic waves having a wide band of frequencies.
It is still a further object of the present invention to provide an antenna with micromagnetic conductors for establishing the inductivity of the antenna along the length of the antenna.
It is a yet a further object of the present invention to provide a novel method for increasing the inductivity of a wire.
These and many other objects and advantages will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of preferred embodiments.